[Hectic]

yeah they have their place.
we have a local guy who is not quite mobile enough these days to run n gun. He built a mount for an m249 and he mostly uses the quad to get from A to B then dismounts and runs his rifle leaving the quad in a good overwatch position and basically sayin "use the saw if ya need to" to anyone close by. Its great for keepin folks in the game who may otherwise not get out to enjoy it.
for milsims or objective based games they can he great for mobile insertions, troop resupply, troop transport etc..
obviously a clear cut set of rules regarding engagement of vehicles and the like needs to be in place but they definately add to the fun factor. Im reminded of a game with hilo insertions, i think someone can recall the name of that.